Impact of grain size on the optoelectronic performance of 2D Ruddlesden-Popper perovskite-based photodetectors

Two-dimensional (2D) Ruddlesden-Popper perovskites have been spotlighted as photodetectors due to their tunable bandgap and high photoluminescence quantum efficiency. The performance of photodetectors is affected by grain boundaries that can trap charge carriers and thereby degrade charge transport in perovskites. To fabricate high-performance photodetectors, it is important to control the grain boundaries of the perovskite film. Here, we use a hot casting method to synthesize highly-crystalline, large-grained films of 2D Ruddlesden-Popper perovskites (C4H9NH3)(2)(CH3NH3)Pb2I7 for use in improving the efficiency of photodetectors. Increasing the grain size of the perovskite film alleviates the effects of grain boundaries. To control the grain size of the film, the composition of the precursor mixture N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) is varied. As the DMSO content increases, the grain size of the film increases from the nanometer to the micrometer scale. Photodetectors fabricated using films with large grains show high photocurrent and on/off ratio compared to those with small grains. This method to synthesize 2D Ruddlesden-Popper perovskite films with tailored grain sizes can facilitate the fabrication of highly-efficient optoelectronic devices.